This invention relates to a length-measuring device adapted to be inserted through a forceps channel in an endoscope so as to measure the size of the affected part in a body cavity of a patient, and also relates to a reference color display device for adjusting a color tone of an image picked up by the endoscope and displayed on a monitor of the endoscope.
One conventional length-measuring device of this general type for use with an endoscope comprises a scale member which has a scale and is bendable into an L-shape. Since the scale member can be projected only in one direction, such a conventional device can be used effectively only when the scale member is projected to a direction which allows an easy observation of the scale member in its field of vision. In addition, it is almost impossible to adjust the direction of projection of the scale member.
To overcome the above problem, there has been proposed a length-measuring device (as disclosed in Japanese Utility Model Publication No. 23441/87) in which an openable member, which can be opened or extended in opposite directions by a resilient force, is inserted into a flexible tube so as to be projected therefrom. The openable member comprises a pair of elongated elements between which a scale member, having scale marks spaced from one another at a predetermined interval, is connected. When the openable member is forced out of the flexible tube, the openable member is opened by its own resilient force, so that the scale member is extended uniformly on opposite sides of the axis of the flexible tube, thereby enabling an accurate length measurement of the affected part at the center of the field of vision of the endoscope.
In this conventional length-measuring device, however, the direction of extension of the scale member (i.e., its angle relative to the flexible tube) is predetermined, and therefore when the scale member 61 approaches the target affected part 62 in a direction oblique thereto as shown in FIG. 1, the size of the affected part can not be measured accurately. Moreover, the openable member must be so constructed that it can be positively opened in the opposite directions. When a measurement is to be effected, the openable member inserted into the flexible tube in its closed condition against its resilient force must be forced out of the flexible by a remote manipulation using an operating wire. Therefore, the operating wire is often buckled or suffers an improper operation. Thus, this conventional device can not always be handled easily. Further, since the overall construction must be firm, the manufacturing cost is increased and the device is too expensive for a scale.
Also, in conventional length-measuring devices, a flexible tube is of a unitary or integral construction from its proximal to distal end. If a length-measuring portion exceeds about 10 mm, it gets caught in the bronchus or other parts. In contrast, if the length-measuring portion is less than about 20 mm, a required measurement can not be carried out in the stomach and the colon. Therefore, the length-measuring portion has to be selected so that its length is in accordance with the part to be measured and with the intended purpose.
With the conventional length-measuring devices, however, since the flexible tube is of a unitary or integral construction from its proximal to distal end, a large set of length-measuring devices having the respective length-measuring portions of different lengths must be provided.
Among the parts of a length-measuring device for use with an endoscope, the length-measuring portion is most susceptible to damage. In the conventional length-measuring devices, even if only the length-measuring portion has been damaged, the whole of the length-measuring device must be replaced by a new one, since the flexible tube is of a unitary or integral construction from its proximal to distal end. Therefore, to avoid the interruption of measurement many length-measuring devices of the same kind must be provided.
Thus, conventionally, many length-measuring devices of the same kind as well as a large set of length-measuring devices of many kinds must be provided. This is undesirable because of increased costs.
Recently, there have been extensively used so-called electronic endoscopes equipped with a solid image pickup element for transmitting an observed image. In this type of endoscope, it is necessary to pre-adjust a color tone of the image displayed on a monitor, and conventionally such adjustment has been carried out using a color chart having three primary colors (i.e., red, green and blue) or a white color chart. More specifically, such a chart is placed on a desk, and this chart is displayed on the monitor through the endoscope, and the color of the image of the chart displayed on the monitor is compared with the color of the actual chart so as to adjust a color tone of the image displayed on the monitor.
However, the endoscope is used to observe the body cavity, and the reflection, scattering and absorption of the illumination light within the body cavity are different from those on the desk, resulting in the difference in the color reproduction of the object. As a result, even if the color tone adjustment is very strictly made on the desk, the object observed within the body cavity can not be accurately reproduced and therefore an accurate diagnosis of the affected part in the body cavity can not be made.
To overcome the above problem, it has been proposed to insert the endoscope into the body cavity so as to carry out a color tone adjustment using an image of the mucous membrane surface within the body cavity. With this method, however, there is no reference based on which the color tone adjustment is to be carried out objectively, and the color tone adjustment is made in accordance with the subject of the operator. Therefore, it is very difficult to accurately reproduce the color.